What change slowly occurs during the main-sequence lifetime of a star?
A) As hydrogen is used up in the core, the fusion rate decreases and reduces the luminosity.
B) It gathers more gas from interstellar space, increasing its mass and hence the luminosity.
C) Its core temperature slowly increases, increasing the fusion rate and hence the luminosity.
D) As the solar wind blows material into space, the decreasing mass reduces pressure in the core, which in turn reduces the fusion rate and the luminosity.
Question 2
The Doppler technique can be used to estimate the semimajor axis of a planet's orbit by
A) measuring the time it takes for the star's line-of-sight velocity to cycle from peak to peak, and using Newton's version of Kepler's Third law.
B) measuring the speed at which the star orbits the mutual center-of-mass of the star and planet, and using Newton's theory of gravity.
C) measuring the asymmetries in the velocity curve.
D) measuring the amount by which the starlight is reduced when the planet transits.
Four main models that describe the relationship between ecosystem function and biodiversity.
Pre–Main-Sequence Evolutionary Tracks
Drag the labels to indicate the change in the size of the reservoir. . .
The second half of life brings a change from outward to inward concerns and from physical to ...
Natural Causes of Climate Change
Mass spectrometry (MS) for Mass, Sequence, and Amino Acid Analyses of Purified Proteins